I have been receiving malicious comments from some Anonymous commentors over 2yrs now. They have cloned my ID, left abusive comments under my name confusing all my blogger friends, palgiarised my work in another blog, made a blog to ridcule me etc etc. And they are still at it at my expense. I have reported this to Blogger many times but to no avail. I don't know how to block people from commenting either. Is there any way I can track the IPs of commentors and block them from my blog for good?
And the short answer, to the question, regrettably, is "No".
You can install a visitor meter, and track your visitors. Once you know the IP address of a problem reader, you can install a product like IP Address Blocker (free).
Blocking them, though, will never be 100% effective. Even with the ability to block by IP address, you'll be wasting your time. Any anonymising proxy server provides any determined attacker free access to the Internet. Anybody who is so uninformed about how to Google for "free proxy server" will, most likely, use an Internet service with dynamic IP addressing. If you block one IP address, you may get your one problem some of the time, and at other times you'll be blocking someone who doesn't care about your blog. Sometimes, you'll be blocking a potential new reader.
Just as you can't block access by IP address, neither can you block access by Blogger / Google account, or by any other identity. With FaceBook, MySpace, or maybe Orkut, all social networking platforms, participation in the program involves an acquired personality and reputation, and verified relationships. Blogger isn't a social networking platform - and Blogger / Google accounts have no value beyond blog ownership. If you wish to create a second Blogger / Google account, to enable you to harass somebody anonymously, that requires no great effort. Absolutely no verification of any mutual friendship is involved.
And all of this addresses direct access to the blog, through the browser. Besides browser access, anybody can subscribe to your blog feed, and read through a syndication feed reader.
The only effective solution, unfortunately, is for you to moderate all comments. Sorry.
All that said, you're welcome to ask Blogger for Person or IP blocking - or you can install IP Address Blocker.